The basis of all imaging modalities exploits some natural phenomenon which varies from tissue to tissue, such as acoustic impedance, nuclear magnetic relaxation, or x-ray attenuation; or, a substance such as a positron or gamma ray emitter is added to the body and its distribution is reconstructed; or, a substance is added to the body which enhances one or more of acoustic impedance, nuclear magnetic relaxation, or x-ray attenuation. Each imaging modality possesses certain characteristics which provide superior performance relative to other modalities of imaging one tissue or another. For example, x-ray contrast angiography has an imaging time less than that which would lead to motion artifact and it possesses high resolution which makes it far superior to any prior known imaging modality for the task of high resolution imaging of veins and arteries. However, x-ray contrast angiography is invasive, requires injection of a noxious contrast agent, and results in exposure to ionizing radiation; therefore, it is not indicated except for patients with severe arterial or venous pathology.